The Research For Earth Pressure Of Expansive Soil Foundation Pit Slope Considering Expansion Force

The relationship between the expansion force and the increment of water content and the relationship between the expansion force anisotropy were determined by experiment.The distribution law of the increment of water content in the expansive soil foundation with depth is analyzed,and the distribution law of the expansion force with depth is deduced.From the point of view of stress state and limit equilibrium in semi-infinite body of expansive soil,the Rankine earth pressure formula considering expansion force is deduced.The main contents are as follows:(1)Based on the theory of lattice expansion and the theory of double electric layer,the formation mechanism of expansive soil expansion force is analyzed.And from the perspective of microstructure to explain the expansion of the anisotropy of the reasons.(2)The relationship between the expansion force and the increment of water content in Chenggong expansive soil and Chengdu expansive soil was studied by intermittent water swelling test.The concept of expansion coefficient and water content increment coefficient was put forward.(3)Based on the idea of constant volume method,the three-way expansion force test device was designed to study the three-way expansion force of expansive soil.The relationship between vertical expansion force and horizontal expansion force was obtained,and the concept of expansion anisotropy coefficient was proposed.(4)The distribution law of water content increment and depth of expansive soil foundation is put forward,and it is verified by field measurement data and centrifugal test.Combined with the expansion coefficient and the water content increment coefficient and the expansion force anisotropy coefficient,the distribution law of horizontal and vertical expansion force with depth is obtained.(5)Based on the theory of Rankine earth pressure and the distribution law of expansion force with depth,the formula of Rankine earth pressure considering expansion force is deduced from the point of view of stress state and limit equilibrium in expansive soil semi-infinite body.(6)Combined with the slope of an expansive soil foundation in Chengdu,the applicability of the formula is verified,and the applicable range and the condition of the formula are put forward.